Ruff Rules dog training? (Or a different reco)

Hi everyone, I recently adopted a 6 month old pup and his separation anxiety is something I’m looking for professional help addressing. (Currently unable to leave my house for any length of time bc he barks to the point my neighbors have complained to me and complaining to the building is obviously next, he also clearly is in distress and I don’t want to fuck him up for life.) I reached out to Ruff Rules and had a call with the owner and the trainer who Duffy (my pup) and I would be working with. They use e-collars and I thought I could be ok with that but I’m feeling really hesitant. They literally only have 5 star reviews on Google and 1 one-star review which seems kind of sus (how is that even possible?). I’m wondering if anyone here has worked with them and how your dog is now (I don’t want a dog that needs to wear an r collar for his whole life in order to be obedient, nor would I want a dog whose decisions are ruled by fear—not to say I don’t believe in any form of discipline, but e-collars seem extreme). I’d also love any trainer recommendations anyone is willing to share. Particularly trainers who skew more on the positive reinforcement side. Thank you!